pub type NewTree<S> = Result<<S as Strategy>::Tree, Reason>;
A new ValueTree from a Strategy when Ok or otherwise Err when a new value-tree can not be produced for some reason such as in the case of filtering with a predicate which always returns false. You should pass in your strategy as the type parameter.
ValueTree
Strategy
Ok
Err
enum NewTree<S> { Ok(<S as Strategy>::Tree), Err(Reason), }
Contains the success value
Contains the error value